<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <script>
        // function f() {};
        // const f = 5;

        // function f() {
        //     const g = 5;
        //     var g;
        // }
        // const MY_OBJECT = {
        //     "key": "value",
        //     "name": "小明"
        // }
        // console.log(MY_OBJECT);
        // MY_OBJECT.name = "小红";
        // console.log(MY_OBJECT);
        // const array = [1, 2, 3, 4];
        // console.log(array);
        // console.log(array[3]);
        // array[4] = 5;
        // console.log(array);
        const MY_OBJECT = {
            "key": "value"
        };
        MY_OBJECT.key = "otherValue";
        console.log(MY_OBJECT.key);
        const MY_ARRAY = ['HTML', 'CSS'];
        MY_ARRAY.push('JAVASCRIPT');
        console.log(MY_ARRAY); //logs ['HTML','CSS','JAVASCRIPT'];
    </script>
</body>

</html>